Mesoporous silica nanoparticles with tunable pore size for tailored gold nanoparticles

The aim of this paper was to verify a possible correlation between the pore-size of meso- porous silica nanoparticles (MSNs) and the sizes of gold nanoparticles (AuNPs) obtained by an impreg- nation of gold(III) chloride hydrate solution in the MSNs, followed by a specific thermal treatment. Mesoporous silica nanoparticles with tunable pore diameter were synthesized via a surfactant-assisted method. Tetraethoxysilane as silica precursor, cetyl- trimethylammonium bromide (CTAB) as surfactant and toluene as swelling agent were used. By varying the CTAB–toluene molar ratio, the average dimension of the pores could be tuned from 2.8 to 5.5 nm. Successively, thiol groups were grafted on the surface of the MSNs. Finally, the thermal evolution of the gold salt, followed by ‘‘in situ’’ X-ray powder diffraction (XRPD) and thermogravimetric analysis (TGA), revealed an evident correlation among the degradation of the thiol groups, the pore dimension of the MSNs and the size of the AuNPs. The samples were characterized by means of nitrogen adsorption– desorption, transmission electron microscopy, small- angle X-ray scattering, XRPD ‘‘in situ’’ by synchro- tron radiation, and ‘‘ex situ’’ by conventional tech- niques, diffuse reflectance infrared Fourier transform spectroscopy, and TGA

E.s.c.a. study of monomodal metal phases in a FAUJASITE matrix

A series of faujasite supported catalysts with monomodal dispersed phases of nickel, palladium, and platinum, exhibiting narrow particle size distributions, are chracterized by X.p.s. (X-ray photoelectron spectroscopy)

Physikalisch-chemische Eigenschaften von zeolithgekapselten Halbleitern und Halbleiter/Platin-Dispersionen im Nanaometerbereich Abschlussbericht

Zeolites of the fanjasite type (x, y) including a partially dealuminated zeolite Y were used as suitable carriers for the preparation and stabilization of highly dispersed semiconductor materials (CdO, ZnO, SnO_2, TiO_2, CdS, ZnS). Platinum of varying dispersion has been generated in zeolites X and Y. Different methods of sample preparation have been applied, and the influence of the preparation conditions on the size and composition of the hosted clusters, on the host-guest interaction and on the optical, electrical and chemical properties of the dispersed materials have been studied. Encapsulated CdO enter into a reversible reaction with CO_2, the rate of reaction strongly depends on the CdO dispersion. TiO_x clusters exhibit at 500 C a reversible redox-behaviour towards H_2 and O_2. (WEN)Available from TIB Hannover: F95B57 / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekSIGLEBundesministerium fuer Forschung und Technologie (BMFT), Bonn (Germany)DEGerman